The BBC’s Stephen Evans in Berlin says using cameras to film people surreptitiously is a sensitive issue in Germany, where privacy is very highly valued.

A Deutsche Bahn spokesman told the BBC that its drones would be used in big depots where vandals enter at night and spray-paint carriages. The drones would have infra-red sensors sophisticated enough for people to be identified, providing key evidence for prosecutions.

But it seems the cameras would be tightly focused within Deutsche Bahn’s own property – people or property outside the depots would not be filmed, so easing any privacy concerns, our correspondent says.

The drone issue is also sensitive in Germany because earlier this month the defence ministry halted an expensive project to develop Germany’s own surveillance drone, called Euro Hawk.